1. Field of the Invention
The present invention relates to a power supply system for supplying electric energy to a rotary electric machine combined with a turbocharger so that the rotary electric machine operates as an electric motor.
2. Prior Art
Many motor vehicle engines are associated with turbochargers for increased output power. The turbocharger has a compressor coupled to a turbine which is driven by the energy of exhaust gases emitted from the engine. The compressor is rotated by the turbine to compress intake air, which is supplied to the engine to increase its output power.
Japanese Laid-Open Patent Publication No. 60(1985)-195329 discloses a turbocharger coupled with an internal combustion engine and incorporating a rotary electric machine which can selectively operate an electric motor or generator. When the energy of exhaust gases from the engine is large, the rotary electric machine operates as a generator to recover the exhaust energy as electric energy. When the engine operates at low speed under high load, i.e., the exhaust energy is small, or the engine is revved up for quick acceleration, electric energy is supplied from a battery to the rotary electric machine to operate it as a motor to assist the turbocharger in supercharging the engine.
With the disclosed proposal, when the driver revs up the engine for quick acceleration, since the battery has an internal resistance, the electric power supplied from the battery to the rotary electric machine does not increase instantaneously, and hence the boost pressure of the turbocharger does not rise quickly. Therefore, the actual motor vehicle acceleration responsive to the driver's action for quick acceleration is slow.